EtherChannel trunking variations

[Mike-]

I've noticed there's a few different ways to configure a layer 2 etherchannel trunk. I was trying to understand which method follows best practices or is more preferred.

method 1: configure the physical interfaces with trunk commands (mode, encapsulation, allowed vlans, channel-group mode)

                 configure second switch's physical interfaces the same as the first and the etherchannel is formed.

method 2: configure the physical interfaces with channel-group mode command only and then configure the port-channel with

                  the trunk commands (mode trunk,encapsulation, allowed vlans). configure second switch the same and the                                   etherchannel is formed.

method 3: combine method 1 and 2, configure physical and port-channel interfaces with trunk commands (seems redundant) 

                but works.

All three methods will form an etherchannel which method should be used?

Where should the trunk commands be applied - physical interface, port-channel interface, or both?

ty for reading

[paul driver · Accepted solution]

Hello

L2 etherchannel
1) default physical interfaces (if possible)
2) configure port-channel in physical interfaces
-- port-channel will be created automatically
3)create trunking encapsulation or access port mode directly in port-channel interface
4)enable physical interfaces "no shut"

L3 etherchannel
1) default physical interfaces (if possible)
2) Config the port-channel interface
3)configure port-channel on physical interfaces with NO switchport and then Ip adddress
4) config physical interrfaces with NO switchport
5) Assign the port-cahnnel ID using channel-group command
6) reset the physical interfaces shut and than No shut

[Joseph W. Doherty]

Ideally, commands that apply to the "physical" aspects of the ports should be applied at the physical port. Commands that apply to the "logical" port-channel, should be applied to port-channel interface. However, depending on the "vintage" if the device and its IOS, you might find that you have to apply the same command at both the physical and logical interfaces or sometimes you find you might apply the commands in just the right order for the Etherchannel to be built. The later switches and IOS versions, tend to more often model the ideal setup.

[Mike-]

where would you apply the trunk commands (switchport mode trunk, switchport trunk encapsulation dot1q, switchport trunk allowed vlan 1,2,3) on the port-channel or physical interfaces.

[paul driver]

Hello

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@Mike- wrote:

where would you apply the trunk commands (switchport mode trunk, switchport trunk encapsulation dot1q, switchport trunk allowed vlan 1,2,3) on the port-channel or physical interfaces.

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As this would be a L2 etherchannel then you would apply it on the logical interface (port-channel )

[Joseph W. Doherty]

Ideally, as Paul also notes all to the port-channel interface, as those commands all apply (logically) to its configuration.